diff --git a/lib/response.js b/lib/response.js
index 9733cf89a..672e0ea93 100644
--- a/lib/response.js
+++ b/lib/response.js
@@ -5,7 +5,6 @@
 var http = require('http');
 var sprintf = require('util').format;
 var url = require('url');
-var util = require('util');
 
 var assert = require('assert-plus');
 var mime = require('mime');
@@ -446,7 +445,7 @@ function patch(Response) {
 
         // Set Content-Type to application/json when
         // res.send is called with an Object instead of calling res.json
-        if (!type && typeof body === 'object' && !util.isBuffer(body)) {
+        if (!type && typeof body === 'object' && !Buffer.isBuffer(body)) {
             type = 'application/json';
         }